# US 4,399,118 A · Process of recovering anhydrous zirconium tetrafluoride > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 4,399,118 A - Document ID: US4399118A - Status: Granted - Kind: A - Application number: 06/277,413 - Filed: 1981-06-25 - Granted: 1983-08-16 - Earliest claimed: 1980-07-05 - Assignees: Metallgesellschaft Aktiengesellschaft - Inventors: Wolfgang Fennemann - Web page: https://patentgrep.com/patent/US4399118A ## CPC - C01G 25/04: Halides - C01G: COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F (metal hydrides {monoborane, diborane or addition complexes thereof} C01B6/00; salts of oxyacids of halogens C01B11/00; peroxides, salts or peroxyacids C01B15/00; thiosulfates, dithionites, polythionates C01B17/64; compounds containing selenium, or tellurium C01B19/00; binary compounds of nitrogen with metals C01B21/06; azides C01B21/08; {compounds containing nitrogen, other non-metals and metal C01B21/082}; metal amides C01B21/092; nitrites C01B21/50; {compounds of noble gases C01B23/0005}; phosphides C01B25/08; salts of oxyacids of phosphorus C01B25/16; carbides C01B32/90; compounds containing silicon C01B33/00; compounds containing boron C01B35/00; compounds having molecular sieve properties but not having base-exchange properties C01B37/00; compounds having molecular sieve and base-exchange properties, e.g. crystalline zeolites, C01B39/00; cyanides C01C3/08; salts of cyanamide C01C3/16; thiocyanates C01C3/20) ## Abstract An improved process for the recovery of substantially anhydrous zirconium tetrafluoride from an aqueous solution of hydrofluoric acid and zirconium fluoride is disclosed wherein the aqueous solution of hydrofluoric acid and zirconium fluoride is sprayed, preferably continuously, into a fluidized bed furnace having a bed comprising zirconium fluoride granules. ## Claims ### Claim 1 In a process for making substantially anhydrous zirconium tetrafluoride by drying zirconium fluoride dissolved in aqueous hydrofluoric acid and subsequently calcining the same to remove the water of crystallization in said zirconium fluoride, the improvement wherein the solution is sprayed continually into a fluidized bed oven with a bed of granulated zirconium fluoride and evaporated and zirconium fluoride containing water of crystallization is calcined in a fluidized bed oven with a bed of granulated zirconium fluoride at 220.degree.-300.degree. C. and drawn off from said fluidized bed oven, continually, as granulated product. ### Claim 2 (depends on 1) A process according to claim 1, wherein the process is carried out employing a hot gas velocity of 1 to 4 meters per second, based upon an empty cross section of the fluidized bed furnace, and zirconium fluoride granules are filled into the furnace up to a bed height of 0.2 to 0.8 m in the non fluidized state. ### Claim 3 (depends on 2) A process according to claim 2, wherein the hot gas velocity is 2 to 3 meters per second and the fluidized bed height corresponds to a non-fluidized bed height of 0.4 to 0.6 meters. ### Claim 4 (depends on 1) A process according to claim 1, wherein the solution of hydrofluoric acid and zirconium fluoride contains more than 200 grams zirconium per liter and more than 50 grams hydrogen fluoride per liter. ### Claim 5 (depends on 4) A process according to claim 4, wherein the solution sprayed into the furnace contains more than 300 grams zirconium per liter and more than 150 grams HF per liter. ### Claim 6 (depends on 4) A process according to claim 4, wherein the solution sprayed into the fluidized bed furnace is formed by dissolving metallic zirconium waste in an aqueous solution of hydrofluoric acid and removing undesired components. ### Claim 7 (depends on 1) A process according to claim 1, wherein zirconium fluoride dust contained in exhaust gas from a fluidized bed furnace is collected in a cyclone and recycled. ### Claim 8 (depends on 1) A process according to claim 1, wherein zirconium fluoride dust contained in the exhaust gas from the fluidized bed furnace is removed in a wet scrubber to which is added an aqueous solution of hydrofluoric acid and zirconium fluoride, the zirconium fluoride dust so recovered being recycled. ### Claim 9 (depends on 8) A process according to claim 8, wherein the aqueous solution of hydrofluoric acid and zirconium fluoride is preheated and subjected to preliminary evaporation in the wet scrubber and is only subsequently sprayed into the fluidized bed furnace. ### Claim 10 (depends on 1) A process according to claim 1, wherein the exhaust gas from the fluidized bed furnace contains zirconium fluoride dust, the zirconium fluoride dust is recovered in two stages, comprising a first stage containing a cyclone and a second stage comprising a wet scrubber. ### Claim 11 (depends on 1) A process according to claim 1, wherein the exhaust from the fluidized bed furnace contains hydrofluoric acid, said exhaust gas is scrubbed with water in a scrubbing tower to remove hydrofluoric acid and the latter is recycled. ### Claim 12 (depends on 1) A process according to claim 1, wherein the evaporation of the solution and calcining of the resultant zirconium fluoride containing water of crystallization is carried out in one operation in the same fluidized bed oven. ### Claim 13 (depends on 12) A process according to claim 12, wherein said process is carried out at a temperature of 220.degree.-300.degree. C. ### Claim 14 (depends on 13) A process according to claim 13, wherein the process is carried out at a temperature of 240.degree.-280.degree. C. ### Claim 15 (depends on 1) A process according to claim 1, wherein the zirconium fluoride granules have a particle size of 0.2 to 4 mm.